1. Field of Invention
The utility model relates to a retractable writing/erasing piece. More particularly, the utility model relates to a structure against sliding back of a retractable writing/erasing piece.
2. Description of Related Art
Retractable writing/erasing pieces, such as retractable lipsticks and retractable paint brushes, use the principle of spiral forced movement and guide groove limit to perform a rotation operation with a linear displacement function, so that an writing/erasing piece (such as a lipstick or a paint brush) can be moved in a retractable manner inside and outside a pipe body, for using or containing the writing/erasing piece.
Referring to FIG. 1, a conventional retractable writing/erasing piece 700 includes a holding pipe 710, an internal pipe 720, a sleeve pipe 730, a slide base 740 and an writing/erasing piece 750.
The internal pipe 720 has a fitting part 721 and a protruding part 722 along a length direction of the internal pipe 720. The fitting part 721 is fitted in an internal part of the holding pipe 710. A pair of straight guide grooves 723 in an opposite direction is disposed on a pipe wall of the protruding part 722. The sleeve pipe 730 covers an external part of the protruding part 722 of the internal pipe 720. A pair of spiral guide slots 731 in an opposite direction is disposed on an internal wall of the sleeve pipe 730. The slide base 740 is contained in an internal part of the protruding part 722 of the internal pipe 720 and a pair of guide protrusions 741 in an opposite direction is disposed on the slide base 740. The pair of guide protrusions 741 passes through the straight guide grooves 723 of the internal pipe 720 and are contained in the pair of spiral guide slots 731 of the sleeve pipe 730 in a protruding manner. The writing/erasing piece 750 is fixed on the slide base 740 and it can be moved with the slide base as a whole.
At the time of retractable use, a user holds the holding pipe 710 and the sleeve pipe 730 with the user's two hands respectively and rotates the holding pipe 710. The holding pipe can drive the internal pipe 720 to rotate as a whole. The internal pipe 720 forces the guide protrusions 741 of the slide base 740 to rotate in a spiral manner along the spiral guide slots 731 of the sleeve pipe 730 through the straight guide grooves 723 of the internal pipe 720. At the same time, the guide protrusions 741 of the slide base 740 are limited by the straight guide grooves 723 of the internal pipe 720 and can slide on straight paths of the straight guide grooves 723. That is, the slide base 740 may rotate in a spiral manner in the sleeve pipe 730 and the internal pipe 720 and slides straightly at the same time, so that the writing/erasing piece 750 fixed on the slide base 740 is retracted with the slide base 740.
However, as shown in FIG. 1, the conventional retractable writing/erasing piece has a drawback of sliding back at the time of erasing or writing. That is, for example, at the time of writing on a piece of paper, the writing force on the paper from the writing/erasing piece 750 may reversely influence the writing/erasing piece 750 and the slide base 740. For the internal pipe 720, which is used to fit with the slide base 740, the straight guide grooves 723 of the internal pipe 720 have a straight groove-shaped configuration and have no resisting structures against the reaction force of writing. Therefore, the reaction force used at the time of writing may force the writing/erasing piece 750 to retract inward very easily, resulting in the writing/erasing piece 750 to slide back. Furthermore, the inconvenient use is caused.
Referring to FIG. 2, in order to protect the writing/erasing piece 750, in general, a cover body 760 for covering may be prepared additionally. The conventional retractable writing/erasing piece 700 uses the cover body 760 to cover and fix an external part of the sleeve pipe 730, so that a linkage relation is formed between the cover body 760 and the sleeve pipe 730.
Such a covering structure of the cover body of the conventional retractable writing/erasing piece may have a drawback of maloperation. That is, when the cover body 760 covers and fixes the sleeve pipe 730, if the user holds the holding pipe 710 and the cover body 760 with the user's two hands respectively and rotates the holding pipe 710 or the cover body 760 accidentally, a relative rotation action will be made between the user and the internal pipe 720 linked to the holding pipe 710 and the sleeve pipe 730 linked to the cover body 760 and as a result the slide base 740 and the writing/erasing piece 750 thereon will be forced to retract accidentally as described above. At this time, the easer 750 protruding outward (such as a lipstick) may be abutted against an internal wall of the cover body 760, resulting in damages to the writing/erasing piece 750.